The present invention relates to a device and procedure for creating and securing a temporary safety space within an elevator hoistway such that a service or maintenance engineer can work with impunity from a car entering the safety space. In particular, the invention provides a stop bar for mounting within the hoistway to prevent movement of the car into the safety space.
In recent years pressure within the elevator industry to reduce the space consumption of installations has increased dramatically. This has resulted in the design of modem elevator systems in which:                a) the entire hoistway length is used for the travel of the car during normal operating conditions. Accordingly there are no permanent, dedicated safety spaces in the head and pit of the hoistway; and        b) the machine is no longer accommodated within a separate room but is also mounted within the hoistway.        
Hence, there is a requirement to provide a temporary safety space within the hoistway of modem systems before maintenance or service work can be carried out. Furthermore, when the machine is mounted in the hoistway, the frequency at which the hoistway must be accessed for maintenance or service work is increased. Accordingly, it is important that the means for creating the temporary safety space can be established and reset quickly and reliably.
Many prior art solutions have been proposed to create the necessary temporary safety spaces. For example, EP-A-0985628, illustrates height adjustable railing members disposed on the top of the roof of an elevator car. During normal elevator operation, the railing members are maintained in a position lower than the highest protrusion from the car roof so that they do not interfere with the travel of the elevator. When maintenance is to be carried out, the railing members are raised to an upright position, thereby establishing a temporary safety space defined between the top of the car and the top of the railing members.
A similar solution is described in WO-A-02085773 wherein a folding framework is mounted on top of the roof of the elevator car. When maintenance is to be carried out, the framework is unfolded and extends vertically above the car to establish a safety space.
A common problem associated with these two solutions is that they are only capable of establishing a safety space in the headroom of the hoistway above the car. Furthermore, the railing members or framework extend vertically through the safety spaces that they create and this may impede the maintenance engineer in carrying out the required work.
A common approach to establishing the required safety space in the pit of the hoistway is described in EP-A-0725033. A buffer is pivotably mounted to the floor of the pit. In normal elevator operating conditions the buffer is retained in a vertical position where it has no influence on the travel of the elevator car. When work is to be carried out in the pit, the buffer is released from its retained position and tilts under gravity into a safety position where it prevents travel of the car into the pit. Similar supports are described in DE-A-10065099. Again, however, these safety devices when creating a safety space in the pit actually extend through the safety space and this may impede the maintenance engineer in carrying out the required work.
U.S. Pat. No. 5,773,771 describes an apparatus for restricting the motion of an elevator car. The apparatus consists of two bolts extensible from either side of a bottom bolster channel supporting the car. In the extended position, the bolts engage with steel plates mounted to the guide rails thereby preventing upward motion of the car. If a service technician is working on the top of the car, it would be difficult, if not impossible, for him to see whether the bolts have extended and correctly engaged with the steel plates. Hence, he cannot be entirely confident that the car has been prevented from moving.